This application claims priority of prior U.S. Provisional Patent Application No. 60/001,919, filed Aug. 4, 1995, and U.S. Provisional Patent Application No. 60/005,280 filed Oct. 10, 1995, which are both incorporated herein by reference.
This invention relates to irrigation methods, and more particularly to a method for providing surface point drip irrigation with enhanced efficiency. The invention also includes an apparatus for providing efficient surface point drip irrigation.
Abroad and in the United States a large percentage of potable, fresh water consumption is utilized for irrigating landscape and ornamental plantings. Prior state of the art irrigation systems utilized for delivering water to landscape plantings were inefficient and contributed greatly to the exhaustion of water reserves in many areas. Spray head systems, which are most commonly used for landscape purposes, lose water to evaporation, runoff, and overspray. The tiny spray droplets necessary to achieve uniform water distribution are vulnerable to wind and are more often than not blown out of the area intended to be irrigated, contributing to the overspray problems. Runoff occurs because the spray heads tend to deliver water too quickly to the periphery of the area to be irrigated and the excess water drains off to adjacent areas. In addition, water droplets from spray head systems tend to impinge on surrounding structures, such as houses, fences, and vehicles, causing discoloration, staining, and other damage.
Low volume surface drip irrigation devices and lines, typically emitting in the range of one-half gallon per hour (gph) to 2 gph, use an extensive network of conduits and emitters which are spaced apart on the surface of the area to be irrigated. Surface drip irrigation also uses manifolds which distribute water to small tubes extending to specific plants. In this surface drip system, water is emitted at rates slow enough to gently soak into the soil directly below the emitter and spread laterally only short distances by capillary action in the soil. Delivery of water in this manner does eliminate runoff, overspray, and evaporation problems, but is only practical for landscape settings in areas not subject to traffic. Even in landscape situations, conventional low flow rate surface drip irrigation systems are not effective for dense plantings unless the emitters are spaced very close to each other, at a distance less than 12 to 18 inches apart. If used in traffic areas such as lawns, low flow surface drip irrigation systems are impractical since the lines must be picked up in between irrigations so as not to be damaged.
Subsurface drip irrigation systems consist of low volume drip emitter lines having one-half gph to two gph emitters placed beneath the soil surface. These subsurface drip irrigation systems provide water directly to the plant root zone without any surface lines. However, the spacing of these conventional subsurface drip lines must be very close, 12 to 18 inches, to provide uniform watering in between the lines. This close spacing requirement makes conventional subsurface drip lines too costly and not practical for a majority of irrigation situations. Even with close spacing of the lines, a majority of the water is lost below the root zones of the plants due to limited capillary action and the effects of gravity. In addition, plant roots have been known to grow into the subsurface emitters, completely blocking flow or at least interfering with the proper flow of water from the emitters. State of the art solutions to this root intrusion problem have consisted of using toxic chemicals impregnated within the lines or run through the irrigation water to kill the roots around the emitters.
The subsurface irrigation system shown in U.S. Pat. No. 5,374,138 represents a significant improvement over conventional subsurface drip irrigation systems. The water deflector positioned beneath the subsurface emitters causes the emitted water to spread laterally to provide uniform watering with wider spacing between emitters. Thus, although it requires the additional deflector component, the subsurface irrigation system shown in U.S. Pat. No. 5,374,138 eliminates some of the problems with conventional subsurface drip irrigation systems.